The rapid compression or expansion of a gas in a plastic syringe is a poor approximation of an adiabatic process. Heat exchange with the walls of the syringe brings the gas to equilibrium in an amount of time that is not significantly greater than the length of the compression or expansion itself. Despite this limitation, it is still possible to measure the pressure changes during a rapid change in volume and calculate an approximation of the pressures for an adiabatic process. From these values the specific heat ratio of the gas can be calculated.